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UNIVERSITY  OF  ILLINOIS 

Agricultural  Experiment  Station 


URBANA,  OCTOBER,  1902. 


BULLETIN  NO.  80. 


METHODS    AND    RESULTS   OF   FIELD   INSECTI- 
CIDE WORK  AGAINST  THE  SAN  JOSE 
SCALE,  1899-1902. 


BY  S.  A.  FORBES,  STATE   ENTOMOLOGIST. 

On  April  11,  1899,  an  emergency  bill  was  approved  by  Gov- 
ernor John  R.  Tanner  of  Illinois  requiring1  the  State  Entomologist 
to  "treat  and  disinfect  once  thoroughly,"  at  the  expense  of  the 
State,  all  orchard  property  which  that  officer  had  reason  to  believe 
had  become  infested  with  the  San  Jose  scale  before  the  year  1899, 
a  fact  which  marked  a  new  departure  in  the  struggle  for  the  con- 
trol of  the  San  Jose  scale  in  Illinois.  Unfortunately,  the  appro- 
priation of  $6,000  made  for  the  expenses  of  this  work  was 
insufficient  for  its  purpose,  being1  indeed  but  half  the  sum  esti- 
mated by  me  as  necessary  to  give  a  single  insecticide  treatment  to 
all  the  premises  then  known  to  be  infested.  This  fact  put  an 
effectual  bar  upon  preliminary  experiments  with  insecticides,  since 
it  was  evidently  my  duty  to  apply  the  appropriation  at  once  and  as 
far  as  it  would  go  to  the  immediate  purpose  expressed  in  the  law, 
that  of  a  thorough  insecticide  treatment  of  infested  premises. 

Being  thus  limited  to  action  on  lines  fixed  by  the  existing  state 

463 


464  BULLETIN  NO.  80.  [October, 

of  our  knowledge  of  insecticide  methods,  it  was  my  first  duty  to 
make  choice  of  the  procedure  which  seemed  most  likely  to  enable 
me  to  exterminate  the  scale  locally  by  a  single  treatment.  This 
choice  necessarily  lay  between  liquid  and  gaseous  insecticides, 
applied  by  spraying1  and  by  fumigation  respectively. 

The  liquid  insecticides  well  enough  known  at  the  time  to  make 
them  practically  available  for  the  destruction  of  the  San  Jose  scale 
were  the  whale-oil  soap  solution  and  the  emulsions  or  mechanical 
mixtures  of  kerosene  and  water.  Crude  petroleum  was  then  com- 
ing into  use,  it  is  true,  but  the  results  reported  were  too  variable 
to  entitle  it  to  confidence  as  both  efficient  and  safe.  To  extermin- 
ate the  scale  in  orchards  with  a  liquid  insecticide  required  that  the 
fluid  should  be  so  distributed  as  to  reach  every  scale  on  every  tree 
in  quantity  sufficient  to  kill  the  insect.  This  was  obviously  an 
impossible  task,  especially  if  we  take  into  account  the  frequency 
with  which  these  minute  scales  are  secreted  under  bark,  behind 
buds,  etc. ;  and  this  conclusion  was  confirmed  by  two  years  of  pre- 
vious experience  with  the  use  of  whale-oil  soap,  during  which 
orchards  and  town  lots  at  twenty-one  localities  in  Illinois  had  been 
carefully  and  thoroughly  treated  by  two  of  my  assistants,  Prof.  H. 
E.  Summers,  now  State  Entomologist  of  Iowa,  and  Mr.  R.  W. 
Braucher,  a  graduate  in  horticulture  from  the  University  of  Illi- 
nois. Subsequent  inspections  of  the  premises  treated  disclosed  the 
fact  that  the  extermination  of  the  scale  was  accomplished  in  no 
case  except  where  every  visibly  infested  tree  and  shrub  was 
destroyed,  together  with  all  adjacent  vegetation  to  which  the  scale 
might  possibly  have  spread. 

The  fumigation  method  had  this  theoretical  advantage  over 
that  with  the  liquid  spray,  that  an  insecticide  vapor  set  free  under 
a  close  tent  enveloping  the  infested  tree  would  be  carried  by  spon- 
taneous diffusion  to  all  parts  of  the  inclosed  space,  and  would  thus 
presumably  reach  every  particle  of  the  infested  surface  and  kill 
every  scale,  provided  the  operation  were  intelligently  and  carefully 
conducted.  There  seemed,  in  short,  a  reasonable  possibility  that 
expert  fumigation  would  exterminate  locally  where  the  conditions 
were  not  unfavorable  to  thorough  work,  while  such  a  result  seemed 
clearly  impossible  with  the  liquid  spray.  I  consequently  decided 
to  make  a  trial  of  orchard  fumigation  with  hydrocyanic  acid  gas, 
applied  after  the  method  which  had  been  in  use  for  several  years 
in  the  citrus  orchards  of  the  Pacific  coast. 

The  opinion  current  among  entomologists  with  respect  to 
fumigation  as  an  orchard  method  was  well  shown  by  statements 
of  experimental  results  appearing  at  about  this  time,  and  especial- 


IQO2.]  THE   SAN   JOSE   SCALE.  465 

i 

ly  by  those  published  in  August,  1898,  in  Bulletin  57  of  the  Mary- 
land Experiment  Station,  and  in  the  fall  of  that  year  in  Bulletin 
No.  17  of  the  Entomological  Division  of  the  U.  S.  Department  of 
Agriculture.  In  the  first  of  these  bulletins,  entitled  "A  Report  on 
the  San  Jose  Scale  in  Maryland  and  Remedies  for  its  Suppression 
and  Control,"  Prof.  W.  G.  Johnson,  State  Entomologist  of  Mary- 
land, gives  an  account  of  various  experiments  with  this  insecticide 
gas,  made  in  the  fall  of  1897  and  the  spring  of  1898  on  bearing 
orchard  trees  in  Maryland.  As  a  conclusion  from  experiments  on 
fifty-three  dwarf  Bartlett  pear-trees  conducted  from  September  27 
to  October  1  by  liberating  gas  under  inclosing  tents,  he  says  (p.  86) 
that  "the  San  Jose  scale  is  entirely  destroyed  by  the  gas  when 
used  on  calm,  dry,  sunny  or  cloudy  days";  that  "the  cost  of 
treatment,  aside  from  the  equipment,  is  less  than  that  for  whale- 
oil  soap";  that  "trees  treated  at  night  with  very  strong  doses  of 
gas  do  not  have  the  foliage  or  dormant  leaf  and  fruit  buds  affected 
at  all,  even  where  double  the  amount  of  gas  ordinarily  used  is 
generated  ";  and  that  "  trees  treated  in  the  morning  before  9  a.  m. 
and  in  the  afternoon  after  4  p.  m.  have  the  foliage  very  little 
affected  by  the  gas."  These  tests  were  thought  by  him  so  grati- 
fying that  a  meeting  of  those  especially  interested  was  called  for  a 
demonstration  of  the  operation,  and  at  a  dinner  served  by  the 
owner  of 'the  infested  premises  all  the  speakers  "were  unanimous 
in  the  opinion  that  the  experiment  was  complete  in  every  respect." 
In  a  later  report  on  this  same  experiment,  read  August  19,  1898,  at 
the  Tenth  Annual  Meeting  of  the  Association  of  Economic  Ento- 
mologists, Professor  Johnson  says:  * 

"In  order  that  I  might  report  the  definite  and  final  results  of 
these  experiments,  I  made  a  careful  examination  of  every  tree  in 
the  orchard  on  Tuesday  and  Wednesday  of  this  week.  Where 
there  were  hundreds  and  thousands  of  scales  breeding  on  the  trees 
at  this  time  last  year  not  one  can  be  found  now,  except  upon  trees 
under  5  feet  in  height  and  on  those  fumigated  when  the  foliage  was 
wet  with  dew  or  fog  or  immediately  after  a  rain,  and  even  on 
these  trees  the  young  larvae  are  very  few  as  compared  with  their 
number  at  this  time  last  year.  Where  the  fruit  was  much  pitted 
and  scarred  by  the  scale  last  year  not  one  has  been  seen  upon  a  pear 
thus  far  this  season. 

"In  all,  the  experiment  is  thoroughly  satisfactory,  in  that  it 
demonstrates  by  actual  trial  that  this  method  can  be  used  in  our 
largest  bearing  orchards,  even  under  the  most  adverse  conditions, 
with  excellent  results." 


*  Bull.  No.  17,  N.  S.,  U.  S.  Dept.  Agr.,  Div.  Ent.,  pp.  41  and  42. 


466  BULLETIN  NO.  80.  [October, 

Fourteen  very  badly  infested  plum-trees  were  also  treated 
March  17  and  18,  1898,  with  hydrocyanic  acid  gas  liberated  under 
tents,  and  no  living-  scales  had  been  found  on  them  three  months 
later.  "The  general  outcome  of  these  experiments,"  says  Profes- 
sor Johnson,*  "up  to  the  present  time,  June  15,  is  so  far  satisfac- 
tory. We  cannot  hope  to  find  a  remedy  for  the  San  Jose  scale  that 
is  more  effective  than  hydrocyanic  acid  gas."  Referring  to  this 
experiment  againf  August  19,  five  months  after  the  treatment  was 
given,  he  says: 

"  The  gas  can  also  be  used  in  the  spring  in  peach,  plum,  and 
apple  orchards  after  the  buds  have  begun  to  unfold.  A  block  of 
one  hundred  six-year  old  plum-trees  at  Annapolis  Junction  was 
fumigated  March  17  and  18,  1898,  and  up  to  the  present  time  not  a 
living  scale  has  been  found  upon  any  trees,  except  those  sprayed 
with  50  and  100  per  cent,  gasoline.  The  trees  in  this  orchard 
were  very  badly  infested,  the  most  of  them  being  so  literally 
covered  it  was  impossible  to  see  the  bark  at  any  point  on  the  trunk 
and  larger  branches. 

"Other  experiments  were  conducted  in  scale-infested  bearing 
orchards  in  May,  June,  and  July,  the  results  of  which  cannot  be 
finally  reported  at  this  time,  except  that  no  living  scales  have  been 
found  upon  any  of  the  fumigated  trees." 

The  operations  reported  in  the  present  paper  can  scarcely  be 
called  experiments,  since  they  were  an  attempt  to  make  practical 
application  in  the  field  of  methods  based  on  the  experimental  work 
and  practical  experience  of  others.  Those  with  hydrocyanic  acid 
gas  may  be  taken,  however,  as  a  test  of  the  fumigation  method  as 
applied  to  common  orchards  and  fruit  plantations  in  southern  Illi- 
nois under  conditions  more  favorable  in  some  respects  and  less 
favorable  in  others  than  those  of  ordinary  orchard  practice.  A 
considerable  series  of  operations  was  carried  on  over  a  large  terri- 
tory by  a  single  party  under  the  direction  of  one  foreman  especially 
selected  and  carefully  instructed  for  this  work,  and  his  manage- 
ment was  doubtless  more  intelligent  and  exact  than  that  of  the 
ordinary  foreman  or  owner  of  an  orchard  would  have  been.  On 
the  other  hand,  the  conditions  which  he  had  to  meet  were  of  course 
much  more  varied  than  those  to  which  any  single  orchardist  would 
be  subject,  and  the  limitations  of  time  and  expense  were  such  that 
the  work  must  move  steadily  forward  whenever  at  all  practicable — 
a  fact  which  made  it  impossible  to  choose  favorable  weather  and 


*Md.  Bull.  57,  p.  90. 

t  Bull.  No.  17,  N.  S.,  U.  S.  Dept.  Agr.,  Div.  Ent.,  p.  42. 


IQ02.]  THE   SAN   JOSE   SCALE.  467 

to  suspend  operations  temporarily  when  it  was  likely  that  the  best 
results  could  not  be  obtained. 

It  has  seemed  to  me,  nevertheless,  that  the  outcome  of  this 
campaign  is  well  worthy  of  report,  since  it  indicates  with  approxi- 
mate fairness  what  can  be  accomplished  by  practical  work  on  a 
large  scale  by  the  intelligent  fruit  grower  so  unfortunate  as  to 
have  become  the  victim  of  the  San  Jose  scale.  Owing  to  the  fact 
that  these  were  not  regarded  as  experimental  but  practical  opera- 
tions only,  the  notes  of  the  work  were  not  as  full  as  I  could  now 
desire.  They  were,  however,  carefully  made  by  competent  men, 
and  are  entirely  reliable  so  far  as  they  go. 

EXPERIENCE  WITH  ORCHARD  FUMIGATION. 

Having  decided  on  an  extensive  practical  trial  of  orchard  fumi- 
gation with  hydrocyanic  acid  gas,  I  found  it  necessary  first  to  pro- 
vide expert  advice  and  supervision  with  respect  to  the  practical 
operation,  with  which  none  of  my  office  force  had  any  personal 
acquaintance,  and  for  this  purpose,  after  considerable  correspond- 
ence, I  secured  the  aid  of  Prof.  Charles  W.  Woodworth,  Assistant 
Professor  of  Entomology  at  the  University  of  California  and  Ento- 
mologist of  the  California  Agricultural  Experiment  Station.  Pro- 
fessor Woodworth  being  a  graduate  of  the  University  of  Illinois 
was  well  known  to  me  personally,  and  was  particularly  useful  to 
us  because  he  had  made  a  special  study  of  fumigation  operations 
in  California.  He  had,  in  fact,  published  an  elaborate  bulletin  on 
"Orchard  Fumigation,"*  which  was  the  principal  reliance  of 
economic  entomologists  interested,  and  remains  to-day  the  best 
brief  practical  treatise  on  the  subject. 

Arriving  in  May,  1899,  he  inspected  parts  of  our  infested  dis- 
tricts, planned  our  equipment  and  superintended  its  manufacture, 
coached  our  first  fumigating  squad,  and  supervised  its  practice 
work — first  on  the  Experiment  Station  farm,  at  Urbana,  and  later 
on  premises  infested  by  the  San  Jose  scale  at  Monticello,  in 
Piatt  county. 

Description  of  Equipment. — Our  tents  to  cover  infested  trees 
and  confine  the  insecticide  gas  liberated  under  them  were  all  made 
of  eight-ounce  canvas,  treated  in  two  different  ways  to  make  them 
impermeable  to  the  gas.  The  first  lot  were  thoroughly  sized  with 
flour  paste  and  covered,  when  dry,  with  a  thin  black  paint;  and 
the  second  lot  were  saturated  with  boiled  linseed  oil  and  left  spread 
out  until  dry.  The  latter  method  of  preparation  proved  the  more 
satisfactory  and  durable.  The  paint  was  likely  to  wear  and  crack 


*  Bull.  122,  Calif.  Apr.  Exper.  Station. 


468  BULLETIN  NO.  80.  [October, 

with  use,  and  the  sizing1  and  painting1  were  more  laborious 
and  costly  than  filling1  with  oil.  The  latter  operation  was  conve- 
niently and  rapidly  performed  (as  shown  in  Plate  I.)  by  the  aid  of  a 
common  spray  pump  provided  with  an  adjustable  nozzle.  Great 
care  was  necessary  that  the  oil  in  the  tents  should  be  thoroughly 
dried  out  before  they  were  folded,  as  otherwise  they  were  liable  to 
heat,  with  the  effect  to  destroy  the  cloth  if  not  to  set  up  spontane- 
ous combustion. 

The  fumigation  outfit  consisted  of  forty-seven  tents,  three 
pairs  of  lifting1  poles,  and  several  sets  of  generators  for  the  prepa- 
ration of  the  gas.  All  except  the  smallest  tents  were  flat  oblong 
sheets  of  canvas,  rounded  at  the  corners  and  sewed  with  overlap- 
ping double  seams.  Seven  of  these  were  SO  X  60  feet  in  diameter, 
ten  were  40  X  48  feet,  and  twenty  were  32  X  38  feet.  There  were 
also  ten  conical  tents  eleven  feet  in  diameter  at  the  base,  used  for 
the  smallest  trees.  For  lifting  these  tents  into  place  there  were 
two  14-foot  scantlings  for  the  smaller  sheet  tents,  two  20-foot  lifts 
made  of  2  X  4  scantlings,  spliced  and  reinforced,  and  two  30-foot 
masts.  Each  pole  when  in  use  was  fitted  with  a  pulley,  through 
which  ran  a  three-fourths  inch  rope,  and  was  also  provided  with 
from  one  to  three  guy-ropes  with  which  to  direct  its  motions  as 
the  tents  were  being  lifted  and  drawn  into  place.  For  trees  twelve 
feet  in  height,  or  less,  one  14-foot  pole  was  the  most  convenient 
lift.  For  those  between  twelve  and  eighteen  feet  one  20-foot  pole 
was  commonly  used  unless  the  top  of  the  tree  was  unusually  broad, 
when  two  were  necessary.  For  still  larger  trees  the  30-foot  masts 
were  used,  one  or  both  according  to  the  size  of  the  tree. 

Description  of  the  Operation. — The  method  of  handling  the 
tents  and  of  liberating  the  gas  was  substantially  the  same  as  that 
described  and  amply  illustrated  in  Professor  Woodworth's  Bulletin 
122,  already  referred  to  (pp.  20-30).  Different  phases  and  varia- 
tions of  the  operation  are  illustrated  in  Plates  II. — VI.  At- 
tempts were  made  at  first  to  fumigate  very  large  trees,  even  when 
two  tents  of  the  largest  size  were  necessary,  one  being  drawn  over 
the  other  so  as  to  lap  upon  it  several  feet.  (See  Plate  V.) 

In  ordinary  work  with  one  pole  three  men  were  required  to 
handle  the  tent,  but  when  two  poles  were  used  a  fourth  man  was 
necessary.  Two  others  were  needed  for  the  process  of  fumigation, 
making  a  squad  of  six  for  the  entire  operation. 

For  peach- and  apple-trees  of  medium  size,  that  is,  12  to  18 
feet  in  height  with  a  spread  of  8  to  15  feet,  a  squad  of  three  men 
with  a  single  20-foot  lifting  pole  did  the  work  most  expeditiously. 
The  pole  was  leaned  against  the  tree  on  the  side  opposite  that 


1902.]  THE    SAN   JOSE    SCALE.  469 

from  which  the  tent  was  to  be  raised,  and  one  end  of  the  rope  run- 
ning- through  the  pulley  at  the  top  of  the  pole  was  thrown  over  the 
center  of  the  tree  and  made  fast  to  the  nearest  edge  of  the  tent. 
The  pole  man  then  hauled  the  tent  upward  to  the  pulley,  or  at 
least  high  enough  to  clear  the  tree,  and  fastened  his  rope,  took  the 
guy-rope  hanging-  from  the  top  of  the  pole,  moved  forward  far 
enough  to  get  the  necessary  leverage  and  drew  the  tent  over  the 
tree,  the  other  two  men  of  the  squad,  one  at  each  side  of  the  tent, 
spreading  it  over  the  sides  of  the  tree  and  adjusting-  it  to  the  top. 
This  operation  is  illustrated  by  Plate  II.,  taken  just  as  the  men 
have  begun  to  pull  the  tent  forward  over  the  tree.  After  the  tent 
had  been  drawn  forward  far  enough  one  tent  man  loosened  the 
pulley  rope  and  let  the  pole  fall,  the  pole  man  detached  the  rope 
from  the  canvas  and  set  the  pole  up  at  another  tree,  while  the  tent 
men  ran  a  binding  rope  about  the  tent  below  the  tree  top,  drew  it 
closely,  and  tied  the  ends  together.  The  borders  of  the  tent  were 
then  laid  close  to  the  ground,  and  weighted  with  earth  if  high 
wind  made  this  necessary,  and  the  tent  was  carefully  searched  for 
possible  leaks. 

The  fumig-ator  prepared  the  charg-e  according  to  the  formula 
of  the  California  Bulletin  for  winter  treatment.  He  measured  the 
circumference  of  the  tent  at  its  largest  diameter  and  estimated  the 
distance  over  the  top  from  his  knowledge  of  the  length  and  width 
of  the  tent  in  use.  The  "acid  man"  measured  the  required 
amount  of  water  and  acid,  poured  them  into  the  generator  and  held 
up  the  border  of  the  tent  while  the  fumigator  put  the  generator  in 
place  near  the  trunk,  charged  it,  and  withdrew.  He  then  quickly 
dropped  the  tent,  seeing  that  it  lay  close  to  the  earth,  permitting 
no  gas  to  escape. 

The  chemicals  used  were  in  the  proportions  indicated  for  a 
.3%  gas  in  the  table  on  page  28  of  the  California  Bulletin.  From 
the  fact  that  the  tent  was  usually  drawn  in  below  the  head  by  a 
rope  while  the  measurement  was  made  round  the  top  of  the  tree  at 
its  greatest  diameter,  the  proportion  of  gas  was  in  most  cases  con- 
siderably stronger  than  .3%.  After  charging  the  tent  with  the 
gas  it  was  left  to  stand  forty  minutes,  at  the  end  of  which  time  it 
was  taken  down  and  moved  to  another  tree. 

Preliminary  Operation  at  Monticello. — Fumigation  can  be  done 
while  the  leaves  are  on  the  trees  only  at  night  or  on  dark  and 
cloudy  days,  and  our  first  attempts  being  made  in  June  (1899),  the 
work  was  done  entirely  at  night.  The  infested  place  nearest  to 
my  office  and  most  convenient  of  access  was  Monticello,  in  Piatt 
county,  where  the  San  Jose  scale  had  been  found  on  a  few  town 


470  BULLETIN  NO.  80.  [October, 

lots  containing1  various  species  of  fruit  and  ornamental  trees  and 
shrubs. 

A  brief  operation  there  demonstrated  at  once  the  impractica- 
bility of  satisfactory  fumigation  work  on  the  miscellaneous  stock 
of  an  ordinary  town  lot.  The  trees  infested  were  of  various  shapes 
and  size,  some  of  them  too  large  to  be  inclosed  by  a  tent.  Trees, 
shrubs,  and  vines  were  often  mingled  in  thicket-like  masses  which 
could  not  be  covered  securely,  and  the  various  kinds  of  vegetation 
which  it  was  necessary  to  treat  were  variously  sensitive  to  the 
withering-  action  of  the  gas. 

After  one  night's  work  of  my  field  party  on  the  grounds  of  a 
prominent  citizen  I  was  summoned  by  telegraph  both  by  the  fore- 
man of  the  fumigating  squad  and  by  the  owner  of  the  premises, 
and  experienced  no  small  difficulty  in  re-establishing  cordial  relations 
between  the  parties  concerned.  To  do  a  thorough  piece  of  work 
some  destruction  of  small  shrubbery  had  been  necessary,  and  the 
leaves  of  several  kinds  of  vines  and  shrubs  were  badly  withered  by 
the  g-as. 

An  inspection  made  the  following  year,  April  14,  1900,  showed 
an  unexpectedly  favorable  result.  On  one  tree  heavily  coated  with 
scales  many  living  specimens  were  found  under  a  crust  of  the  dead, 
but  elsewhere  two  hours'  search  disclosed  but  three  living-  scales. 
The  place  had  been  temporarily  saved  from  serious  damage  by  the 
scale,  but  at  a  cost  exceeding  the  value  of  the  rescued  property, 
and  the  failure  to  exterminate  was  evident.  No  attempt  has  since 
been  made  by  me  to  treat  miscellaneous  trees  and  shrubs  on  town 
lots  by  the  fumigation  method. 

The  trees  and  shrubbery  on  twenty-one  lots  in  this  town — all 
on  which  the  San  Jose  scale  could  be  found — were  sprayed  with  a 
twenty  per  cent,  soap  emulsion  of  kerosene  April  10-19,  1900. 

Orchard  Fumigation  at  Sparta.  —  A  region  of  more  than 
twenty-five  square  miles  about  Sparta,  in  Randolph  county,  was 
known  by  me  to  be  generally  infested  with  the  San  Jose  scale  in 
the  fall  of  1899,  this  and  the  neighborhood  of  Richview,  in  an 
adjoining  county,  being  the  most  important  infested  districts 
discovered  in  Illinois  up  to  that  time.  After  the  completion 
of  the  the  annual  nursery  inspection  of  1899,  preparations  were 
made  for  a  general  campaign  with  the  fumigation  equipment  in 
this  neighborhood,  and  my  party  took  the  field  at  Sparta  Octo- 
ber 18  under  the  charge  of  Mr.  E.  C-  Green,  with  Mr.  R.  W. 
Braucher  as  inspector.  Here  it  continued  actively  at  work  for  the 
next  two  months,  by  which  time  it  was  evident  that  with  the 
appropriations  available  it  was  altogether  impossible  to  treat  the 


IQO2.]  THE    SAN   JOSE   SCALE.  471 

infested  premises  of  this  region  fully  by  the  fumigation  method, 
and  the  party  was  transferred  to  Rich  view,  in  Washing-ton  county, 
for  work  on  another  plan. 

The  Sparta  district  was  mainly  one  of  small  farm  orchards,  of 
which  only  here  and  there  one  had  expanded  in  a  way  to  make  its 
fruit  an  important  part  of  the  owner's  crop.  Many  of  the  infest- 
ed orchards  were  very  old  or  contained  some  very  old  trees  of  a 
size  to  make  fumigation  exceedingly  difficult  or  to  put  it  altogether 
out  of  the  question  (Plate  VII.).  Taking-  one  orchard  with 
another,  infested  trees  of  every  size  were  to  be  found,  from  those 
recently  set  out  to  giant  survivors  of  the  plantings  of  the  early  pio- 
neers. The  owners  had  often  neglected  their  trees  until  it  seemed 
a  waste  of  public  funds  to  attempt  to  save  them  when  infested  by 
the  San  Jose  scale  ;  but  as  the  law  gave  me  no  power  to  condemn 
a  tree  until  its  value  was  altogether  gone,  I  was  obliged  to  treat 
such  trees  whether  they  were  worth  the  cost  of  treatment  or  not. 
Osage  orange  hedges  had  become  extensively  infested  by  the  scale 
in  this  district,  in  one  instance  at  a  distance  of  a  quarter  of  a  mile 
from  the  nearest  orchard.  Thickets  of  escaped  fruit  trees  were 
growing  beside  the  roads  in  fence  corners,  or  by  the  borders  of 
woods,  and  these  were  often  more  or  less  infested,  and  as  the 
country  still  contained  many  remnants  of  its  original  forest  cover- 
ing there  seemed  a  considerable  probability  that  the  scale  was  ob- 
scurely distributed  far  and  wide  through  this  forest  growth. 

Notwithstanding  the  discouraging  features  of  the  situation 
we  made  a  serious  attempt  at  fumigation  here,  which  presently 
took  the  form,  however,  of  a  preliminary  operation  to  show  what 
was  practicable  by  this  method  in  such  a  place,  and  what  must  be 
otherwise  provided  for.  , 

General  Results. — From  our  experience  at  this  place  it  soon 
became  clear  that  local  extermination  of  the  scale  was  impractica- 
ble by  fumigation,  or  by  a  single  operation  of  any  kind,  unless 
power  were  given  to  destroy  utterly  everything  infested  which 
could  not  be  cleared  of  the  scale  at  once  ;  that  many  of  the  trees 
were  too  large  to  fumigate,  and  hence  could  be  treated  only  with 
a  liquid  spray  ;  that  the  fumigation  process  in  such  a  region  was 
slow  and  extremely  costly  as  compared  with  any  other  known  ;  and 
that  weather  conditions  often  greatly  diminished  its  efficiency  by 
making-  it  practically  impossible  to  hold  the  gas  under  the  tents  at 
full  strength  long  enough  to  produce  the  desired  effect.  In  very 
windy  weather  no  care  in  the  management  could  prevent  the  rapid 
escape  of  the  gas,  as  was  shown  by  the  strong  smell  of  it  on  the 
leeward  side  of  the  tent  and  the  absence  of  any  such  smell  when 


472  BULLETIN  NO.  80.  [October, 

the  tree  was  uncovered  ;  and  when  the  weather  was  very  cold  the 
watery  vapor  from  the  generators  condensed  on  the  canvas  and  im- 
mediately froze,  lining-  the  tents  with  ice.  In  this  condition  they 
were  likely  to  break  when  folded  in  handling,  and  the  brittle 
branches  of  the  tree  breaking  when  the  heavy  tent  was  hauled 
across  the  top,  the  tents  were  often  torn  by  the  jagged  stubs. 

Furthermore,  it  appeared  from  subsequent  inspections  that  the 
cases  were  few  in  which  all  the  scales  on  a  tree  appeared  to  be 
killed,  and  the  frequency  with  which  scales  were  found  alive  on  the 
lower  part  of  the  trunk,  while  all  were  seemingly  dead  on  the  re- 
mainder of  the  tree,  showed  that  the  insecticide  gas  did  not  diffuse 
equally  under  the  tent,  but  tended  to  rise,  leaving  near  the  ground 
a  layer  of  insufficiently  poisoned  air.  As  this  unequal  diffusion  of 
the  gas  has  since  been  demonstrated  in  closed  rooms,  —  a  fact  now 
taken  into  account  in  the  construction  of  fumigation  houses, — it  is 
evident  that  we  have  here  a  serious  objection  to  the  whole  process 
of  orchard  fumigation  for  the  San  Jose  scale.  We  now  know  that 
peculiar  methods  and  special  precautions  are  necessary  to  secure  an 
equal  diffusion  of  the  gas,  even  in  the  air-tight  rooms  used  in  nur- 
sery fumigation,  and  with  the  varied  conditions  and  rapid  work  of 
orchard  fumigation  it  is  clearly  impossible  to  secure  a  uniform 
action  even  in  the  average  case. 

Details  of  the  Work  and  its  Results. — The  following  items  con- 
cerning thirteen  representative  orchards  fumigated  at  Sparta  are 
taken  from  the  field  reports  of  the  foreman  and  inspector. 

No.  1.  On  the  place  of  Alvin  Blair  three  hundred  and  ninety- 
five  trees,  most  of  them  peach,  were  fumigated  from  October  20  to- 
November  4.  They  were  of  medium  size  except  a  few  of  the  apple- 
trees,  which  were  very  large,  requiring  the  use  of  two  of  the 
largest  tents  lapped  together  over  one  tree  and  tied  down  with 
ropes.  The  peach-trees  had  been  severely  cut  back  the  preced- 
ing spring  previous  to  spraying  with  whale-oil  soap  (see  Plate 
IX.),  and  the  sharp  stubs  remaining  punctured  the  tents,  thus 
making  necessary  constant  inspection  and  frequent  repair  of  leaks. 
No  doubt  some  gas  escaped  and  some  trees  were  imperfectly  treat- 
ed. A  high  wind  was  blowing  when  much  of  the  work  was  done, 
and  great  embarrassment  was  also  caused  by  cold  and  rainy 
weather,  the  tents  tearing  easily  when  wet  and  frozen.  This 
place  was  inspected  September  10  of  the  following  year  (1900), 
and  badly  infested  peach-trees  were  found  scattered  through  the 
orchard,  the  wood  of  two  years'  growth  sometimes  almost  incrusted. 
In  one  row  which  was  carefully  examined  the  scale  was  found  on 
seventy-three  per  cent,  of  the  trees. 


IQ02.]  THE   SAN   JOSE   SCALE.  473 

No.  2.  On  J.  W.  Robinson's  place  one  hundred  and  seventy- 
seven  trees,  thirty-six  grape-vines,  and  seven  shrubs  were  fumi- 
gated October  18-20.  This  place  had  also  been  sprayed  with 
whale-oil  soap  early  in  May  of  the  same  year  to  check  the  spread 
of  the  scale.  September  10,  1900,  twenty-seven  trees  were  inspect- 
ed, and  scales  were  found  on  twenty-one.  Two  of  these  were  very 
badly  infested,  but  it  was  surmised  that  these  had  been  left  with- 
out treatment  on  the  promise  of  the  owner  to  destroy  them  as 
worthless.  ^ 

No.  3.  The  place  of  Mrs.  J.  B.  Hayer  was  probably  the  one 
first  infested  in  this  whole  region,  one  orchard  having-  been  com- 
pletely destroyed  by  the  owner  because  of  injury  by  the  scale.  The 
trees  remaining  were  mainly  apple  and  pear,  most  of  them  very 
badly  infested.  One  hundred  and  seventy  trees  were  fumigated 
here  November  24-27,  high  winds  causing-  considerable  trouble. 
September  12  of  the  following  year  no  badly  infested  trees  were 
seen,  but  living  scales  were  found  on  thirty  per  cent,  of  the  trees. 

No.  4.  On  the  place  of  Jefferson  Porch  both  peach-  and  apple- 
trees  were  badly  infested.  The  fumigation  squad  was  here  from 
November  28  to  December  2,  treating-  eighty  trees  of  medium  size. 
September  11  of  the  following-  year  living-  scales  were  found  on 
fifty-three  per  cent,  of  the  trees,  but  were  numerous  on  none. 

No.  5.  On  the  place  of  J.  K.  Blair  ninety-one  peach-trees  were 
fumigated  November  6  and  8,  some  of  these  badly  infested  and 
others  slig-htly  so.  Twenty-eig-ht  large  old  apple-  and  peach-trees 
were  marked  for  removal.  Those  fumigated  were  planted  so  close 
together  that  they  could  be  treated  only  with  great  difficulty,  and 
the  canvas  was  badly  torn  in  the  operation.  The  treatment  proved, 
however,  to  be  unusually  effective,  and  living-  scales  were  found 
September  8,  1900,  on  only  two  of  the  trees.  A  plum-tree  badly 
infested  when  fumigated  appeared  at  this  time  to  be  entirely  free 
of  living  scales. 

No.  6.  In  an  orchard  of  several  acres  belonging  to  Sylvester 
Brown  most  of  the  trees  were  infested,  some  of  them  badly  so. 
Many  of  them  were  large,  requiring  two  of  the  largest  tents  to  cover 
them.  Ninety-one  trees  were  fumigated  November  8-11,  and 
thirty-five  were  marked  for  removal,  eight  of  them  large  old  apple- 
trees.  September  10,  1900,  but  five  infested  trees  could  be  found 
in  this  orchard,  and  on  one  of  the  old  apple-trees  badly  infested 
the  preceding  year  not  a  living  scale  could  be  detected. 

No.  7.  November  18-23,  two  hundred  and  twelve  small  to 
medium  trees  were  fumigated  on  Mr.  James  Davidson's  place,  a 
few  apple-  and  two  pear-trees  too  large  to  be  covered  by  tents  be- 


474        •  BULLETIN  NO.  80.  [October, 

ing  left  for  the  spraying-  gang.  September  11,  1900,  living-  scales 
were  found  on  four  of  these  trees,  but  all  the  others  were  appar- 
ently clean. 

No.  8.  November  23  and  24,  twenty-three  trees  were  fumi- 
gated, together  with  a  few  grape-vines,  on  the  place  of  Charles 
Lott.  Although  a  strong  north  wind  made  the  handling  of  the 
tents  unusually  difficult,  no  living-  scales  could  be  found  on  this 
place  September  11,  1900,  except  on  one  apple-tree  left  for  removal 
by  the  owner  as  worthless,  but  which  he  had  failed  to  destroy. 

No.  9.  December  4,  1899,  seventy  small  trees  were  fumigated 
on  William  Wilson's  place,  thirty  per  cent,  of  which  were  found 
infested  by  a  few  living-  scales  September  11  of  the  following-  year. 

No.  10.  On  Thomas  H.  Wilson's  place  a  few  trees  were  re- 
ported infested  in  a  six-acre  orchard  of  apple  and  peach.  One  hun- 
dred and  twenty-six  trees  were  fumigated  here  December  4  and  5, 
and  September  11  of  the  following  year  living  scales  were  found 
on  ninety  per  cent,  of  them.  The  wind  was  troublesome  at  this 
place,  the  canvas  was  stiff  with  ice  and  easily  torn,  and  lumps  of 
frozen  earth  were  dug  up  to  hold  the  bottom  of  the  tent  in  place. 

No.  11.  A  thirty-five-acre  orchard  of  Thomas  Brown's,  in 
which  a  number  of  infested  peach-trees  were  found  along  one  side, 
was  treated  December  7-16,  348  trees  being  fumigated  here  in  all. 
These  ranged  from  six  to  twenty-five  feet  in  height,  the  majority 
requiring  tents  of  medium  size.  On  the  14th  of  December  a  moist 
snow  stopped  the  work,  which  was  resumed  the  following  day  in 
snow  about  a  foot  deep.  September  12,  1900,  a  few  scales  were 
found  on  five  of  the  trees,  but  the  others  were  seemingly  clear. 

No.  12.  On  the  place  of  Frank  Blair  occupied  by  William 
Blair  was  a  badly  infested  young  orchard  and  two  infested  hedges 
near  by.  One  hundred  and  eighty-five  trees  of  medium  size  were 
fumigated  here  November  11-15.  September  8  of  the  following 
year  twenty-nine  of  these  trees  were  critically  examined,  and  six- 
teen were  found  very  slightly  infested.  The  bases  of  the  trunks  of 
some  were,  however,  well  stocked  with  living  scales,  and  sprouts 
growing  up  from  near  the  base  had  thus  become  heavily  infested. 

No.  1?.  On  the  place  of  James  A.  Wood  sixty  trees,  some  of 
them  badly  infested,  were  fumigated  December  6,  and  one  was 
cut  down  as  worthless  because  of  the  scale.  A  few  were  very 
large,  requiring  two  of  the  largest  tents  to  cover  them.  Septem- 
ber 11,  1900,  four  of  these  trees  were  still  badly  infested,  and  thir- 
ty-five per  cent,  of  them  showed  more  or  less  of  the  scale. 

Orchard  Fumigation  at  Richview. — With  the  transfer  from 
Sparta  to  Richview  the  problem  of  local  extermination  was  materi- 


1902.]  THE   SAN   JOSE   SCALE.  475 

ally  simplified.  The  latter  town  is  in  the  midst  of  a  typical  fruit 
district.  The  orchards  are  large  and  mainly  well  kept  ;  they  are 
comparatively  young-  and  uniform  and  contain  but  few  overgrown 
trees  ;  the  infested  district  was  not  hopelessly  large  ;  and  the  sur- 
roundings were  not  unfavorable  to  thorough  work,  the  presence  of 
Osage  orange  hedges  being  the  most  unfavorable  feature. 

With  the  advantage  of  two  months  of  active  field  experience 
my  party  was  prepared  to  do  thorough  and  careful  work  at  this 
place,  and  the  instructions  were  to  spare  no  labor  or  pains  to  kill 
every  scale  in  every  infested  orchard.  Hydrocyanic  acid  gas  was 
used  for  all  trees  to  which  it  was  adapted,  but  the  attempt  to 
cover  very  large  trees  with  tents  was  given  up,  such  trees  being 
severely  pruned  and  thoroughly  sprayed  with  kerosene  emulsion 
diluted  to  contain  twenty  per  cent,  of  the  oil.  (See  Plate  VIII.) 

Great  care  was  taken  that  the  tents  should  be  kept  in  perfect 
repair,  and  every  part  of  the  work  was  carried  on  under  the  imme- 
diate supervision  of  Mr.  Green,  foreman  of  the  squad,  or  of  Mr. 
Braucher,  the  inspector.  The  treatment  was  applied  thoroughly, 
not  only  to  all  trees  on  which  the  scale  could  be  found  but  to  oth- 
ers near  enough  to  stand  in  any  danger  of  infestation.  Owners  of 
infested  hedges  were  induced  to  destroy  them  (Plate  IX.) ;  trees 
very  badly  infested  were,  as  a  rule,  cut  out  and  burned  ;  and,  in 
short,  nothing  was  omitted  which  would  help  to  make  the  work 
effective  and  complete. 

We  had  also  at  Richview  the  especial  advantage  of  the  coun- 
tenance, aid,  and  influence  of  Mr.  J.  W.  Stanton,  Treasurer  of  the 
State  Horticultural  Society,  himself  an  owner  of  large  fruit  farms, 
and  a  man  whose  character  and  experience  made  his  judgment  and 
advice  acceptable  to  his  entire  neighborhood. 

The  work  here  began  December  22,  1899,  and  continued  to 
February  10,  by  which  time  all  premises  known  to  be  infested  had 
been  treated,  with  the  exception  of  one  large  apple  orchard  so  far 
removed  from  any  other  fruit  plantation  that  no  danger  was  ap- 
prehended of  an  escape  of  the  scale  from  it  to  any  other  property. 
A  general  inspection  of  this  region  was  made  after  a  lapse  of  two 
years,  in  March,  1902,  all  the  places  previously  infested  being  then 
very  carefully  examined  by  Mr.  R.  W.  Braucher,  my  most  acute 
and  experienced  inspector. 

Details  of  the  Richview  Work. — No.  1.  The  first  place  treated 
at  Richview  was  an  orchard  of  apples  and  peaches  on  the  James 
Newcome  Estate,  owned  at  the  time  by  J.  W.  Stanton  and  George 
McCoy.  2,087  trees  of  small  to  medium  size  were  treated  by  fumi- 
gation between  December  22  and  January  4.  On  four  of  these 


476  BULLETIN  NO.  80.  [  October, 

days — December  29  and  30  and  January  1  and  2 — the  weather  was 
extremely  cold,  and  fires  were  kept  burning-  in  the  orchards  to  keep 
the  water  from  freezing-.  The  canvas  was  so  stiff  with  ice  that  it 
was  easily  torn,  and  it  was  difficult  to  bring-  the  skirts  of  the  tent 
so  close  to  the  ground  as  to  prevent  all  leakag-e  of  g-as.  When  the 
tents  were  removed  from  the  trees,  at  the  end  of  forty  minutes,  no 
odor  of  the  g-as  was  perceptible  during-  this  coldest  weather,  al- 
though at  other  times  it  was  very  distinct.  This  work  was  done 
under  the  constant  personal  supervision  of  either  Mr.  Braucher  or 
Mr.  Green. 

March  6,  1902,  many  trees  in  this  orchard  were  badly  infest- 
ed, and  some  of  them  were  almost  completely  incrusted  by  the 
scale. 

No.  2.  In  the  apple  orchard  of  Levi  Walker,  a  few  trees  along- 
one  side  were  found  infested  and  also  an  adjoining  Osage  orange 
hedg-e.  This  place  was  fumigated  January  8  and  9,  during  a  Jan- 
uary thaw  following  upon  two  days  of  rain.  January  8  mud  and 
water  were  ankle  deep  in  that  part  of  the  orchard  where  the  work 
was  done.  The  canvas  became  very  heavy  and  five  men  were 
needed  to  handle  the  tents.  One  hundred  and  thirty-five  trees 
were  fumigated,  ranging  in  height  from  twelve  to  twenty  feet, 
and  the  infested  Osage  orange  hedge  was  cut  out  about  a  month 
later.'  Forty-seven  rods  of  high  and  heavy  hedge  were  cut  away, 
and  the  stumps  were  sprayed  with  strong  kerosene  emulsion. 

March  7  to  12,  1902,  this  orchard  and  hedge  were  examined  by 
Mr.  Braucher.  An  occasional  tree  was  found  slighly  infested  with 
the  scale  in  that  part  of  the  orchard  fumigated  two  years  before, 
and  the  hedge,  which  had  grown  up  from  the  roots,  was  again 
badly  infested. 

No.  3.  In  a  small  orchard  belonging  to  I.  H.  Jones  forty-seven 
trees  were  fumigated  January  10-12.  One  old  peach-tree  was  des- 
troyed, and  two  plum-trees  were  subsequently  sprayed  with  kero- 
sene emulsion.  March  15,  1902,  three  trees  on  this  place  were 
found  slightly  infested  with  the  scale. 

No.  4.  January  12,  sixty  apple-  and  pear-trees  of  medium  size 
and  smaller  were  fumigated  in  a  small  infested  orchard  belonging 
to  Mr.  James  Ewing,  many  of  them  completely  incrusted  by  the 
scale.  March  14,  1902,  only  three  infested  trees  could  be  found  on 
this  place,  and  the  scale  was  scarce  on  these. 

No.  5.  In  the  orchard  of  George  McCoy,  composed  of  trees  of 
medium  size  or  larger,  were  a  few  slightly  infested  trees.  All 
these  were  fumigated  January  13,  together  with  others  around 
them  for  several  rows  in  all  directions,  one  hundred  and  thirty- 


Ig02.]  THE   SAN   JOSE    SCALE.  477 

eight  trees  in  all.  Owing-  to  the  discovery  of  a  single  suspicious 
scale  on  an  adjoining  Osage  orange  hedge  a  considerable  section 
of  the  hedge  was  destroyed  February  10.  March  6,  1902,  the  part 
of  this  orchard  treated  two  years  before  had  again  become  slightly 
infested,  and  the  adjoining  hedge  was  reported  as  in  bad  condition 
from  the  presence  of  the  scale. 

No.  6.  The  orchard  of  Jasper  Wilgus  was  generally  and  vari- 
ously infested,  many  of  the  trees  being  in  rather  bad  condition. 
Two  hundred  and  seventy-eight  small  to  medium  trees  were  fumi- 
gated here  on  the  15th  and  16th  of  January,  two  hundred  peach- 
and  apple-trees  were  destroyed  by  the  owner  as  worthless,  and  one 
hundred  and  sixty-one  trees  too  large  to  fumigate  were  sprayed 
with  twenty  per  cent,  kerosene  emulsion  January  23-26.  February 
9,  three  rods  of  hedge  infested  by  the  scale  were  removed  and  des- 
troyed. This  place  was  inspected  February  28  and  March  14,  1902, 
at  which  time  some  of  the  trees  in  that  part  of  the  orchard  which 
had  been  fumigated  were  again  badly  infested,  as  well  as  a  consid- 
erable length  of  the  Osage  orange  hedge.  On  the  large  trees 
which  had  been  sprayed  with  kerosene,  on  the  other  hand,  only  a 
few  scales  could  be  found. 

No.  7.  In  a  small  orchard  on  a  town  lot  belonging  to  William 
Edwards  forty-one  trees  were  fumigated  January  17,  including  sev- 
eral reported  as  infested.  March  1,  1902,  the  scale  could  be  found 
only  on  a  single  tree. 

No.  8.  In  a  small  infested  orchard  belonging  to  Thomas  Hoke 
forty-six  badly  infested  trees  were  fumigated  January  10  to  20,  and 
fifteen  were  destroyed  as  worthless.  March  1,  1902,  thirty  five  of 
the  trees  were  re-examined,  and  thirty-two  of  them  were  generally 
infested  by  the  scale  to  an  extent  to  require  another  treatment 
without  delay. 

No.  9.  January  27  one  hundred  and  seventy-two  peach-  and 
apple-trees  were  fumigated  in  an  infested  orchard  belonging  to 
Mrs.  E.  A.  Glenn,  and  eleven  trees  were  sprayed  with  20  per  cent, 
kerosene  emulsion.  According  to  a  report  of  an  inspection  of 
eighty-eight  of  the  fumigated  trees  made  February  28  and  March 
1,  1902,  thirty-two  of  these  were  again  infested  to  an  extent  to  re- 
quire speedy  treatment  as  a  protection  to  adjacent  orchards  in 
which  the  scale  had  not  been  found. 

No.  10.  On  J.  Bennett's  place  fifteen  trees  were  fumigated 
January  17,  and  on  February  2  one  large  apple-tree  was  sprayed 
with  kerosene  emulsion.  March  1,  1902,  two  small  trees  slightly 
infested  furnished  the  only  remaining  traces  of  the  scale. 

No.  11.     One  hundred  and  thirteen  trees  were  fumigated  Jan- 


478  BULLETIN  NO.  80.  \_October, 

uary  20  and  22  in  an  infested  orchard  belonging-  to  W.  H.  Grove; 
and  February  2,  sixty-seven  trees  additional  were  sprayed  with  a 
twenty  per  cent,  emulsion  of  kerosene.  March  1,  1902,  twenty-nine 
of  these  orchard  trees  were  found  infested,  and  also  a  few  peach 
sprouts  along-  one  side  of  the  place. 

No.  12.  The  pear  and  apple  orchards  of  J.  W.  Stanton  were 
somewhat  infested  at  this  time,  although  they  had  been  extensive- 
ly treated  with  insecticide  sprays  since  the  first  discovery  of  the 
scale  on  his  premises  three  years  before.  Seven  hundred  and  sev- 
enteen apple-trees  in  one  corner  of  an  infested  orchard  were  futni- 
g-ated  January  22-25,  and  about  thirty  larg-e  peach-trees  were  re- 
moved. January  27-29  nine  hundred  dwarf  pears  were  sprayed 
with  kerosene  emulsion,  a  part  of  it  containing-  twenty  per  cent,  of 
kerosene,  and  the  remainder,  by  mistake  of  an  assistant,  fifty  per 
cent.  With  this  latter  streng-th  over  one  hundred  trees  were  treat- 
ed. Two  years  later,  February  28  and  March  4  and  5,  1902,  all 
these  orchards  were  critically  examined  and  only  a  few  scattering- 
scales  were  found.  The  trees  treated  with  a  fifty  per  cent,  emul- 
sion had  not  been  injured  in  the  least.  It  should  be  said  that  this 
orchard  was  in  excellent  condition,  its  owner  being-  an  experienced 
and  careful  fruit  grower,  and  everything-  was  consequently  favora- 
ble to  effective  work. 

No.  13.  January  25  and  26  thirty-five  larg-e  trees  were  fumi- 
gated in  an  infested  orchard  of  apple  and  peach  belonging-  to  S. 
Newcome.  March  15,  1902,  Inspector  Braucher  reported  that 
eighteen  trees  were  slig-htly  infested,  but  less  so  than  two  years 
before. 

No.  14.  Nineteen  trees  were  fumigated  January  26  in  an  in- 
fested apple  orchard  belonging  to  Edward  Aplin,  and  some  peach- 
trees  were  destroyed  at  the  owner's  request.  March  14,  1902,  a  few 
slightly  infested  trees  were  found. 

No.  15.  January  26  nineteen  trees  were  fumigated  on  Mrs.  R. 
R.  S.  Vasey's  place,  and  February  6  one  very  large  tree  was  spray- 
ed with  kerosene  emulsion.  March  14,  1902,  three  slightly  infest- 
ed trees  were  found  by  my  inspector  on  these  premises. 

No.  16.  On  Dr.  W.  Smeaton's  place,  in  charge  of  L.  D.  Allen, 
sixty-seven  trees,  mostly  peach  and  some  of  them  badly  infested, 
were  fumigated  January  27.  This  place  was  inspected  March  12, 
1902,  and  a  few  trees  found  slightly  infested.  A  hedge  on  the 
place  was  now  infested  and  required  treatment. 

No.  17.  January  26  an  infested  tree  on  the  place  of  Mrs. 
Simeon  Shinall  was  fumigated,  but  an  inspection  of  it  March  15, 
1902,  showed  it  to  be  slightly  infested. 


1902.]  THE   SAN   JOSE   SCALE.  479 

Comment  on  the  above  Results. —  The  foregoing  statements  of 
conditions  found  at  Sparta  and  at  Richview  are  not  strictly  com- 
parable with  each  other  because  the  inspection  at  Sparta  was 
made  in  September,  1900,  eight  or  nine  months  after  the  insecticide 
treatment,  and  that  at  Richview  was  made  in  February  and 
March,  1902.  The  Sparta  region  was  inspected  in  the  midst  of  the 
first  growing  season  after  the  trees  were  treated  and  before  the 
time  of  most  rapid  multiplication  of  the  scale, — which  is  usually 
the  month  of  October  in  southern  Illinois, — while  the  Richview 
inspection  was  made  after  a  lapse  of  two  complete  seasons  of 
growth  and  multiplication. 

The  best  results  of  orchard  fumigation  obtained  by  my  parties 
are  shown  by  the  inspection  reports  on  places  5,  6,  7,  and  8  in  the 
Sparta  district,  and  3,  4,  7,  and  12  at  Richview.  In  the  four 
Sparta  orchards,  where  317  trees  were  sprayed  in  the  fall  of  1899, 
the  scale  could  be  found  on  only  11  of  them  in  September,  1900; 
ami  in  the  first  three  Richview  orchards,  where  148  trees  were 
treated,  only  seven  proved  to  be  infested  two  years  later.  At  Sparta 
Nc.  8  a  close  approximation  seems  to  have  been  made  to  a  complete 
extermination  of  the  scale  and  the  same  may  be  said  of  Richview 
No.  7,  and  perhaps,  also,  of  No.  12. 

The  most  serious  obstacle  to  work  was  that  offered  by  cold 
and  freezing  weather,  as  is  shown  especially  by  No.  10  at  Sparta 
and  No.  1  at  Richview,  High  winds  were  less  disadvantageous 
(see  Nos.  3  and  8  of  the  Sparta  district),  and  excellent  results  may 
be  obtained  in  spite  of  them,  as  shown  especially  by  No.  8.  Nei- 
ther snow  nor  wet  weather  diminished  noticeably  the  effectiveness 
of  the  operation,  as  shown  by  No.  11  at  Sparta  and  No.  2  at  Rich- 
view.  It  would  appear  from  Sparta  No.  6  that  large  trees  can  be 
fumigated  effectively  by  the  use  of  two  tents  at  once,  overlapping 
by  their  edges. 

In  none  of  the  cases  here  described  was  even  a  single  orchard 
completely  cleared  of  the  scale, — unless  possibly  at  Sparta  No.  7, — 
a  fact  which  taken  in  connection  with  the  costliness  of  fumigation 
as  compared  with  other  equally  if  not  more  effective  methods  puts 
it  completely  out  of  the  field  for  ordinary  orchard  work  in  Illinois. 

COST  OF  ORCHARD  FUMIGATION. 

The  expenses  of  our  work  are  divisible  roughly  into  those  for 
exploration  and  inspection  of  the  infested  territory,  for  equipment, 
for  transportation  of  the  outfit  and  party  from  place  to  place,  for 
supervision  and  general  management,  and  for  the  operation  of 
fumigation  itself.  All  except  the  last  of  these  were  so  largely 


480  BULLETIN  NO.  80.  [October, 

special  to  our  undertaking-  and  so  little  like  those  of  the  ordinary 
owner  of  an  orchard  that  they  would  be  of  little  or  no  practical  in- 
terest. For  the  great  variety  of  trees  on  which  we  had  to  work  in 
fumigating-  everything  in  an  extensive  district,  we  needed  a 
greater  variety  and  a  larg-er  number  of  tents  than  would  usually 
be  necessary  in  private  work,  and  the  cost  of  extensive  inspection 
and  that  of  transportation  would  be  avoided  by  the  orchardist 
working-  only  on  his  own  premises.  The  expenses  of  actual  futni- 
g-ation,  however,  would  be  about  the  same  ordinarily  as  in  our 
work,  provided  that  the  private  owner  had  to  hire  all  his  labor  but 
made  no  charg-e  for  his  own  services,  and  this  item  of  our  account 
will  consequently  be  useful  for  comparison.  It  must  be  remem- 
bered, as  explained  elsewhere,  that  the  necessity  we  were  under 
to  keep  the  party  at  work  in  g-ood  weather  and  bad,  whenever  work 
was  at  all  possible,  increased  the  averag-e  cost  of  fumigation  per 
tree  above  what  it  would  have  been  if  our  men  could  have  been 
laid  by  in  bad  weather  without  expense,  or  could  have  been  other- 
wise profitably  employed. 

At  Sparta  2,297  trees  were  fumigated  on  seventeen  different 
premises— an  average  of  135  trees  at  each  place.  1,160  Ibs.  of 
cyanide  of  potassium  and  290  gallons  of  common  sulphuric  acid 
were  used  in  this  work,  at  a  cost  of  $412;  and  1,700  hours  of  labor 
were  required,  at  10  cents  an  hour.  The  total  expense  was  $582 — 
an  average  of  25  cents  a  tree. 

At  Richview,  where  the  trees  were  smaller  and  conditions  were 
more  favorable  generally,  3,879  trees  were  fumigated  on  seventeen 
different  places,  an  average  of  228  trees  on  each.  994  Ibs.  of  cya- 
nide of  potassium  and  248  gallons  of  sulphuric  acid  were  used,  at  a 
cost  of  $353;  and  the  bill  for  labor  was  $113  for  1,130  hours — an 
average,  all  told,  of  12  cents  a  tree. 

Taking  both  places  together,  the  cost  of  the  mere  fumigation  of 
6,176  trees  was  $1,048,  or  approximately  17  cents  a  tree.  Compari- 
sons of  effectiveness  and  cost  by  this  and  other  methods  will  be  made 
later  in  this  article,  after  a  detail  and  discussion  of  the  results  of 
the  use  of  the  fluid  insecticides. 

TREATMENT  WITH  WHALE-OIL  SOAP. 

Our  experience  in  the  treatment  of  many  thousand  trees  with 
this  well-known  insecticide,  prepared  in  the  usual  strength  of  two 
pounds  to  the  gallon  of  water,  has  merely  served  to  confirm  the 
common  conclusions  with  respect  to  it.  It  has  proved  to  be  very 
efficient  for  the  destruction  of  the  scale,  killing  practically  all 
reached  by  it  ;  has  done  no  injury  to  trees  or  shrubs  ;  but  has 


1902.]  THE   SAN   JOSE   SCALE.  481 

proven  dangerous  to  the  fruit  buds  of  the  peach  unless  applied  in 
spring1  after  the  buds  begin  to  swell.  It  is  much  the  most  expen- 
sive of  the  sprays  of  which  we  have  made  use,  costing  at  the  rate 
of  $6.50  per  hundred  gallons,  and  has  also  been  the  most  inconve- 
nient of  application  in  cold  weather.  This  solution  is  only  fluid 
while  warm,  becoming  of  a  semi-gelatinous  consistency  when 
entirely  cool,  and  if,  owing  to  the  clogging  of  the  nozzle,  'it  was 
necessary  to  stop  its  flow  for  a  little  time,  the  delivery  hose  was 
sure  to  clog  and  fill  if  the  weather  was  much  below  freezing.  Our 
work  was  all  done  with  potash  soaps,  but  I  have  made  no  compar- 
ative tests  of  these  and  soda  soaps,  and  have  failed  to  find  any  pub- 
lished evidence  in  support  of  the  very  common  preference  of  the 
former  as  an  insecticide. 

EXPERIENCE  WITH  KEROSENE  EMULSION. 

The  heavy  cost  of  the  whale-oil  soap  solution,  the  annoyance 
and  delay  caused  by  its  clogging  in  the  delivery  hose  in  very  cold 
weather,  and  the  practical  certainty  that  a  large  proportion,  if  not 
all,  of  the  fruit  buds  of  peach-trees  sprayed  with  it  would  be  killed 
except  in  the  comparatively  small  number  of  cases  where  our  treat- 
ment could  be  applied  in  spring,  led  to  the  substitution  for  it  dur- 
ing the  winter  of  1899  and  1900  of  an  emulsion  of  kerosene  diluted 
with  water  and  varying  in  actual  practice  to  contain  from  20  to  25 
per  cent,  of  kerosene. 

Beginning  at  Sparta  and  Richview  in  January,  1900,  its  use 
was  continued  through  February  and  March  at  Carterville  and 
Albion,  and  at  Monticello  until  April  19,  by  which  time  the  season 
was  too  far  advanced  to  permit  further  use  of  this  winter  spray 
without  injury  to  the  unfolding  leaves.  5,315  trees  were  sprayed 
with  it  in  these  places  and  at  this  time.  November  8  of  this  same 
year  insecticide  work  was  begun  at  Quincy,  where  a  25  per  cent, 
kerosene  emulsion  was  used  on  one  large  and  three  small  orchards 
November  14  to  December  19,  and  a  20  per  cent,  emulsion  on  an- 
other at  New  Boston,  in  Mercer  county,  December  29-31.  At 
Barry,  in  Pike  county,  an  apple  orchard  of  500  trees  was  sprayed 
with  it,  partly  as  an  experiment,  January  7-14,  1901.  The  mix- 
ture used  there  was  in  three  different  strengths,  containing  20  per 
cent.,  25  per  cent.,  and  40  per  cent,  of  kerosene  respectively. 

The  orchard  insecticide  work  of  the  fall  of  1901  began  Novem- 
ber 25,  and  at  first  a  25  per  cent,  emulsion  of  kerosene  was  used  for 
everything.  December  9,  however,  instructions  were  issued  to  spray 
all  peach-  and  plum-trees  with  the  so-called  California  wash  of 
lime,  sulphur,  and  salt,  and  to  use  the  kerosene  emulsion  for 


482  BULLETIN  NO.  80.  [October, 

other  trees  only  on  sunny  days,  substituting  whale-oil  soap  for  it 
whenever  the  weather  was  dark.  Finally,  on  February  5,  1902, 
my  chief  inspector,  Mr.  Green,  was  directed  to  stop  the  use  of  ker- 
osene altogether,  and  to  dispose  of  his  stock  on  hand.  This  order 
was  made  in  consequence  of  a  report  by  Mr.  Braucher,  then  en- 
gaged in  inspecting  orchards  which  had  been  treated  by  us  in  the 
fall  and  winter  of  the  preceding  year,  to  the  effect  that  apple-trees 
had  apparently  been  injured  in  November  of  that  year  in  the  New 
Boston  orchard  mentioned  above  by  a  20  per  cent,  emulsion  applied 
by  Mr.  Green. 

Kerosene  Emulsion  at  Richvieiu. — The  operations  at  Rich  view 
in  1900  fairly  represent  the  cost  and  the  results.  One  thousand 
five  hundred  and  thirty-five  trees  were  treated  at  this  place  at  an 
expense  of  $17.65  for  oil,  $37.65  for  labor  at  ten  cents  an  hour,  and 
$16.73  for  the  hire  of  a  horse — a  total  of  $72.03,  or  an  average  of 
somewhat  less  than  five  cents  a  tree.*  The  results  reported  can- 
not be  readily  summarized  and  are  consequently  given  in  detail  for 
several  typical  lots  of  trees. 

No.  1.  One  hundred  and  fifteen  apple-,  pear-,  and  peach-trees, 
most  of  them  large  and  old,  treated  with  20  per  cent,  emulsion 
January  26-29  and  February  1,  1900,  on  the  premises  of  Mr.  G.  T. 
Hoke — two  town  lots  and  an  old  orchard  near  by.  October  8,  1900, 
a  few  living  scales  were  found  on  some  of  the  peach-trees  that  had 
been  sprayed.  March  11,  1902,  the  trees  on  the  town  lots  were 
slightly  infested,  and  a  few  scales  were  found  on  some  of  the 
orchard  trees. 

No.  2.  Nine  trees  on  a  town  lot  belonging  to  Mr.  K.  Mark 
were  treated  February  1,  1900.  March  11,  1902,  5  of  the  9  trees 
were  slightly  infested. 

No.  3.  Twenty  infested  trees  varying  from  medium  to  large 
belonging  to  Mr.  Charles  Miller  were  sprayed  February  1  and  2, 
1900,  and  March  11,  1902,  scales  were  found  on  only  one  of  these 
trees. 

No.  4.  Twelve  badly  infested  peach-trees,  small  to  medium 
in  size,  sprayed  February  3,  1900,  were  found  generally  infested, 
but  not  heavily  so,  on  March  22,  1902. 

No.  5.  Of  36  infested  peach-trees  belonging  to  Mr.  John  Gayr 
treated  February  23,  1900,  20  were  found  infested  March  3,  1902. 


*The  average  cost  of  spraying  5,710  trees,  from  January,  1000,  to  January, 
1001,  at  five  different  localities  was  4^  cents  a  tree.  The  premises  treated  were 
mainly  town  lots,  requiring  frequent  interruption  of  operations  and  consequently 
increased  expense.  In  three  orchards  near  Barry  1,486  trees  were  sprayed,, 
and  at  a  cost  of  3.2  cents  per  tree. 


IQ02.]  THE    SAN   JOSE   SCALE.  483 

No.  6.  February  3-6,  1900,  4  infested  trees  on  a  town  lot  be- 
longing- to  Mr.  N.  F.  Tate,  and  a  large  pear-tree  also  infested  on 
another  lot,  were  sprayed  with  20  per  cent,  emulsion.  A  large  apple- 
tree  was  destroyed  at  this  time  as  practically  worthless  from  the 
abundance  of  the  scale.  Two  years  later,  March  13,  1 902,  all  5 
of  the  trees  sprayed  were  slightly  infested,  as  were  also  sprouts 
from  the  root  of  the  apple-tree  destroyed. 

No.  7.  February  6,  1900,  12  orchard  trees  belonging-  to  Mr. 
C.  P.  Cooper  were  sprayed,  and  March  12,  1902,  two  years  later,  the 
scale  was  found  on  2  of  these  trees. 

No.  8.  Three  large  peach-trees  in  an  orchard  of  Mrs.  M.  A. 
Robins  were  sprayed  February  6,  1900,  and  March  17,  1902,  two 
years  later,  2  of  the  3  were  slightly  infested. 

Similar  data  are  given  for  seven  other  premises,  all  pointing  to 
the  conclusion  that  trees  were  rarely  cleared  of  the  scale  completely 
by  this  insecticide  spray,  but  that  a  single  treatment  would  serve  as 
an  efficient  protection  for  at  least  two  years.  In  several  of  these 
cases  another  insecticide  treatment  would  be  necessary  by  the  end 
of  another  year  at  the  farthest.  No  injury  to  trees  of  any  kind 
was  done  by  this  twenty  per  cent,  emulsion  distributed  at  Rich- 
view  in  January  and  February  of  this  year. 

Experience  at  Carterville,  Albion,  and  Monticello,  Spring  of 
/poo. — Beginning  with  March  5  and  continuing  to  March  17,  2,272 
trees,  belonging  to  six  owners,  at  Carterville  were  sprayed  with  a 
twenty  percent,  emulsion  with  Mr.  Green  in  charge.  These  trees 
were  of  mixed  kinds,  mainly  apple,  but  including  also  plum,  pear, 
and  peach.  Subsequent  visits  made  in  1901  and  1902  showed  that 
no  injury  whatever  was  done  to  any  of  these  trees. 

At  Albion  674  trees  were  treated,  mostly  peach  but  with  some 
apple,  plum,  and  pear,  all  receiving  a  twenty  per  cent,  emulsion 
between  March  23  and  29.  These  trees  were  scattered  in  small 
lots  upon  twenty-four  town  premises.  This  place  was  repeatedly 
visited  by  inspectors  and  spraying  parties  up  to  the  winter  of  1902, 
and  no  trace  of  injury  by  the  kerosene  treatment  was  discovered. 

Kssentially  the  same  statement  may  be  made  with  respect  to 
Monticello,  where  843  fruit  trees  of  various  kinds,  including  apple, 
peach,  and  plum,  were  sprayed  on  twenty-two  premises  from  April 
10  to  19,  no  appreciable  injury  following. 

Experiment  -with  Kerosene  Emulsion  at  Barry. — The  only 
strict  experiment  with  this  spray  made  by  us  in  the  winter  of  1901 
was  the  last  operation  of  the  season — that  in  the  apple  orchard  of 
Belah  Wright,  at  Barry,  Pike  county.  Five  hundred  trees  were 
treated  here  January  7-14,  150  of  them  with  20  per  cent,  emulsion, 


484  BULLETIN  NO.  80.  [October, 

223  with  a  25  per  cent.,  and  127  at  a  strength  of  40  per  cent.  Jan- 
uary 7  and  8,  when  the  20  and  25  per  cent,  mixtures  were  applied, 
the  weather  was  cloudy  and  rather  warm.  January  9  a  sleety  rain 
fell,  covering-  the  trees  with  ice  which  continued  until  January  14, 
when  the  40  per  cent,  mixture  was  applied.  This  was  a  clear  day 
with  no  wind. 

Regarding  this  as  an  experimental  test  of  the  effects  of  the 
soap  emulsion  of  kerosene,  both  on  the  scale  and  on  the  tree,  I  sent 
Mr.  Braucher  for  an  inspection  of  this  orchard  October  2,  1901,  be- 
fore beginning  the  fall  work  of  the  season.  A  general  view  of  the 
orchard  showed  that  the  treatment  as  a  whole  had  been  very  ef- 
fective, but  that  more  scales  had  survived  in  that  section  of  the  or- 
chard treated  with  the  20  per  cent,  emulsion  than  in  either  of  the 
other  two.  Two  trees  were  found,  in  fact,  in  this  part  which 
were  regarded  as  badly  infested,  and  on  several  others  scattering 
scales  were  seen.  None  of  the  trees  had  been  noticeably  injured 
even  by  the  strongest  spray,  if  exception  be  made  of  a  small  spot  of 
deadened  bark  on  a  single  tree  which  might  possibly  have  been 
due  to  it.  In  the  section  treated  with  40  per  cent,  of  kerosene 
scarcely  a  scale  escaped,  and  even  where  25  per  cent,  was  used  the 
treatment  was  very  effective. 

At  New  Boston. — December  22,  1900,  in  an  orchard  belonging 
to  W.  Esley,  near  New  Boston,  in  Mercer  county,  both  apple-  and 
peach-trees  were  found  generally  infested,  some  of  the  former  be- 
ing practically  incrusted.  December  24-28  this  orchard  was 
pruned  and  prepared  for  spraying  by  Mr.  Green.  December  29 
and  31,  239  trees  were  treated  with  a  20  per  cent,  emulsion  of  kero- 
sene, the  29th  being  very  cold,  clear,  and  bright,  and  the  31st  cold 
and  dull.  Part  of  the  peach-trees  were  pruned  as  a  preparation  for 
treatment  and  were  then  thoroughly  sprayed,  but  another  lot  of 
peaches,  not  known  to  be  infested,  were  pruned  slightly  or  not  at 
all  previous  to  the  insecticide  spray.  January  17,  1902,  an  inspec- 
tion by  Mr.  Braucher  showed  that  ten  of  the  thirteen  small  peach- 
trees  which  had  been  pruned  were  dead  and  another  badly  injured, 
while  the  adjacent  lot,  not  pruned,  were  not  reported  as  injured  at 
all.  Of  the  75  young  apple-trees  generally  and  badly  infested 
which  had  been  treated  December  29,  20  were  dead  and  10  were 
badly  injured,  and  on  26  there  were  still  small  numbers  of  living 
scales.  Ten-year-old  apple-trees  sprayed  December  31  were  not  in- 
jured, neither  were  cherry,  pear,  and  plum  sprayed  at  the  same  time. 

No  explanation  of  this  extraordinary  occurrence  can  be  sug- 
gested. The  oil,  although  bought  locally,  was  said  to  be  of  the 
same  brand  and  grade  as  that  used  elsewhere  without  injury,  and 


1002.]  THE    SAN   JOSE   SCALE.  485 

the  treatment  was  not  peculiar  in  any  discernible  particular.  On 
this  account,  even  more  than  if  a  satisfactory  explanation  were 
forthcoming-,  the  occurrence  suggested  caution  in  the  use  of  the 
kerosene  emulsion,  and  Mr.  Braucher's  report  was  followed  at  once, 
as  already  stated,  by  orders  to  substitute  whale-oil  soap  for  the 
emulsion  in  all  our  field  work. 

Kerosene  Emulsion  at  Qumcy.—Two  other  cases  of  apparent 
injury  to  trees  by  kerosene  emulsion  occurred  in  the  fall  of  1900  at 
Quincy. 

No.  1.  In  an  orchard  mainly  of  peach-trees,  belonging-  to  Mr. 
Gustav  Klarner,  7  trees  were  found  October  3,  1900,  infested  with 
the  San  Jose  scale,  and  were  destroyed  with  the  owner's  consent 
November  8.  Mr.  Klarner  wished  to  be  sure  that  no  scale  re- 
mained on  his  place,  and  in  view  of  the  probability  that  other  trees 
in  the  orchard  were  obscurely  infested  Mr.  Green  proceeded  to 
spray  all  the  trees,  997  in  number,  near  enough  those  infested  to 
endanger  them  in  the  least.  After  pruning  them  carefully  as  a 
means  of  securing  a  thorough  distribution  of  the  spray,  he  began 
the  treatment  November  14  with  an  emulsion  containing-  23  per 
cent,  of  kerosene. 

The  weather  was  unusually  variable,  but  not  cold  at  any  time. 
The  first  day  of  the  operation  was  cloudy  and  dull,  and  the  second, 
November  15,  was  sunny  and  bright.  Nothing  was  done  on  the 
16th,  17th,  18th,  or  20th  because  of  rains,  and  only  a  little  on  the 
19th,  which  was  a  damp  and  misty  day.  Spraying  was  resumed 
on  the  21st  and  continued  until  the  23d,  the  first  two  of  these 
days  being  bright  and  the  last  one  dull. 

There  was  nothing  uncommon  in  this  operation  except  that 
the  brand  of  oil,  purchased  in  the  local  market,  was  different  from 
that  ordinarily  used  by  us  elsewhere,  and  the  emulsion  was  also  a 
little  stronger  than  the  usual  20  per  cent. 

This  orchard  was  inspected  by  Mr.  Braucher  between  January 
20  and  February  17,  1902,  that  is  fifteen  months  after  treatment, 
but  by  this  time  extensive  changes  had  been  made  in  it  by  the 
owner,  who  had  replaced  many  trees  said  to  have  been  injured  or 
killed,  and  had  dug  out  a  part  of  a  large  block,  planting  the  ground 
to  raspberries.  In  the  part  still  standing  324  trees  were  either 
wanting  or  had  been  replaced  by  others  the  preceding  spring.  Mr. 
Klarner  himself  estimated  his  loss  at  700  peach-trees. 

No.  2.  On  the  premises  of  Wm.  C.  Burgdorf,  near  Quincy, 
were  scattered  plots  of  mixed  fruit-trees, — pear,  peach,  cherry,  and 
apple, — among  which  Mr.  Green  found  November  10,  1900,  trees 
infested  with  the  San  Jose  scale.  Two  small  blocks  of  eighteen- 


486  BULLETIN  NO.  80.  [October, 

year  old  peach-trees,  196  in  all,  were  grubbed  out  by  the  owner  of 
his  own  accord  between  November  12  and  21,  and  248  fruit  trees  re- 
maining- were  sprayed  by  Mr.  Green  with  twenty-five  per  cent,  kero- 
sene emulsion  November  30  and  December  3.  The  weather  was 
bright,  with  little  or  no  wind.  February  18  and  19,  1902,  Mr. 
Braucher  found  that  the  trees  treated  in  this  orchard  were  either 
killed  or  injured,  the  peach  having-  suffered  worst.  Injury  to  the 
cherry  is  also  especially  mentioned.  Four  or  five  of  these  trees 
had  been  grubbed  out,  and  some  others  were  nearly  dead.  The 
San  Jose  scale  was  detected  at  this  time  on  ten  peach-trees,  all 
in  one  lot  which  had  been  sprayed  by  Mr.  Green. 

No.  3.  On  the  place  of  August  Burgdorf,  at  Quincy,  was  an 
orchard  of  fifteen-year-old  apple-trees  which,  because  of  its  close 
proximity  to  a  badly  infested  tree  belonging  to  a  neighbor,  Mr. 
Green  regarded  as  probably  infested.  Thirty-six  of  these  trees 
nearest  the  infested  tree  were  sprayed  by  him  with  a  25  per  cent, 
emulsion  December  4 — a  fair  day  with  a  light  breeze — together 
with  four  other  trees  near  by.  February  18,  1902,  this  apple  orchard 
was  found  by  Mr.  Braucher  uninjured  and  apparently  free  from 
the  scale,  but  two  trees  in  an  adjacent  lot  which  had  not  been 
sprayed  were  at  this  time  slightly  infested. 

No.  4.  On  Mr.  Henry  Hoffmeister's  place,  near  Quincy,  H.  O. 
Woodworth  found  November  30,  1899,  two  apple-trees  infested  by 
the  San  Jose  scale,  and  in  November,  1 900,  Mr.  Green  reported 
three  apple-trees  badly  infested  and  several  peach-trees  slightly  so. 
These  apple-trees  and  a  few  of  the  peach-trees  were  taken  out  by 
the  owner  and  all  the  remainder  were  pruned  by  him  preparatory 
to  the  application  of  the  spray.  In  Mr.  Green's  judgment,  as  ex- 
pressed at  the  time,  this  pruning  was  too  severe  and  not  according 
to  his  instructions,  which  he  had  illustrated  by  the  sample  pruning 
of  a  single  tree.  An  emulsion  containing  twenty-six  per  cent,  of 
kerosene  was  used  on  this  place  by  Mr.  Green  December  17  to  19, 
the  weather  of  the  first  day  being  dull  and  that  of  the  other  two 
days  bright  and  fair.  February  15,  1902,  the  trees  on  this  place 
were  in  good  condition  according  to  Mr.  Braucher's  report,  except 
for  some  apparent  injury  by  the  spray.  It  was  said,  however,  by 
the  tenant  in  charge  that  some  of  the  trees  sprayed  had  died  and 
had  been  taken  out. 

All  the  orchards  on  the  two  places  just  described  were  sprayed 
with  the  same  oil  as  that  used  on  Mr.  Klarner's  place  (No.  1),  and 
the  general  remarks  made  concerning  that  place  apply  also  to  these. 


Ig02.]  THE   SAN   JOSE   SCALE.  4&7 

KEROSENE    EMULSION.     SEASON   OF  1901-02. 

The  fact  has  already  been  mentioned  that  from  November  25, 
1901,  to  December  9  of  the  same  year  a  soap  emulsion  containing 
25  per  cent,  of  kerosene  was  used  by  our  spraying-  parties  on  every- 
thing treated  by  them,  and  that  from  December  9  to  February  5  it 
was  applied  to  all  trees  but  peach  and  plum,  these  being  treated 
with  the  California  wash.  At  the  latter  date  its  use  was  wholly 
abandoned  and  whale-oil  soap  was  substituted  for  it,  this  and  the 
California  wash  being- the  only  insecticides  applied  during  the  re- 
mainder of  the  season. 

The  emulsion  was  used  within  this  period  on  6,536  trees  at  14 
different  places  in  central  and  southern  Illinois.  The  larg-est  use 
of  it  was  made  at  Makanda  and  Carterville,  where  it  was  applied 
to  1,975  and  1,770  trees  respectively.  August  15  and  16,  1902,  Mr. 
Titus  visited  these  two  localities  under  instructions  to  look  care- 
fully into  the  condition  of  the  trees  which  had  been  treated  with 
this  kerosene  spray,  and  according-  to  his  report  no  damage  had 
been  done  at  either  place  to  trees  of  any  description,  while  the 
effect  on  the  scale  was  very  satisfactory. 

January  6-9,  1902,  about  700  trees  belonging-  to  Dr.  H.  V. 
Ferrell,  of  Carterville,  mainly  apple  but  some  of  them  cherry  and 
pear,  were  treated  with  a  25  per  cent,  emulsion,  and  130  trees,  all 
apple  but  one — which  was  a  pear  tree — were  sprayed  at  the  same 
time  on  the  place  of  Mr.  J.  W.  Ghent.  August  15,  no  injury  from 
spraying  could  be  detected  in  these  orchards,  which  bore  a  crop  of 
apples  equal  to  the  average  crop  of  uninfested  orchards  in  the 
neighborhood. 

At  Makanda  450  trees  belonging-  to  S.  Y.  Dickinson,  mainly 
apple  with  a  few  cherry  and  plum,  received  the  same  kerosene 
treatment  December  11-28,  1901.  The  apple  orchard  was  on  a 
steep  clay  slope  and  appeared  to  have  suffered  considerably  from 
the  drought  of  the  preceding  year,  but  there  was  no  tangible  evi- 
dence Aug.  16  of  any  injury  due  to  the  insecticide  treatment  applied. 

On  the  place  of  Lammer  Brothers,  about  225  apple-  and  pear- 
trees  were  treated  December  31  with  a  25  per  cent,  emulsion,  and 
owing  to  some  apprehension  of  injury  on  the  part  of  the  owners 
this  place  was  very  thoroughly  examined  by  Mr.  Titus  August  16. 
The  trees  were  absolutely  uninjured,  as  were  also  530  apple-trees 
belonging  to  Mr.  S.  A.  Carr,  treated  in  the  same  way  and  exam- 
ined at  the  same  time. 

Indeed  the  only  injury  done  to  trees  by  kerosene  during  the 
winter  of  1901-02  of  which  I  have  been  able  to  learn,  was  that  to 
peaches  on  the  place  of  Mr.  Henry  Archer,  near  Beamington, 


488  BULLETIN  NO.  80.  [October, 

Sangamon  county.  A  mixed  orchard  of  513  trees  was  sprayed 
here  November  29  to  December  4  with  a  23  per  cent,  emulsion  of 
kerosene.  The  orchard  was  variously  composed  of  young-  and  old 
trees,  and  included  apple,  pear,  plum,  peach,  cherry  and  quince. 
The  young-  trees  sprayed — peach,  cherry,  and  pear — were  wholly 
uninjured,  but  certain  old  peach-trees  were,  with  few  exceptions, 
dead  by  July  12,  when  the  place  was  inspected  at -my  direction  by 
one  of  my  nursery  inspectors,  Dr.  W.  C.  Bag-ley.  From  his  report 
it  appears  that  the  young-  orchard  above  mentioned  had  been  cul- 
tivated the  preceding-  year,  but  that  the  old  orchard  in  which  the 
dead  peach-trees  stood  had  received  but  little  care,  not  having 
been  cultivated  for  several  years,  and  that  the  trees  of  various 
kinds  remaining-  in  it,  both  those  which  had  not  been  sprayed  and 
those  which  had  survived  the  treatment,  were  in  poor  and  un- 
thrifty condition.  The  weather  of  the  days  during-  which  the  old- 
er peach-trees  were  sprayed  was  somewhat  unfavorable,  with  fogs, 
mists,  and  cloudy  sky.  No  harm  was  done  to  apple  or  quince.  A  few 
of  the  pear-trees  had  died  after  being-  sprayed,  but  as  the  blig-ht  was 
prevalent  on  the  place,  their  death  was  probably  due  to  that  disease. 
An  apple  orchard  belonging-  to  Mr.  I.  N.  Lowe,  near  Auburn,  in 
Sang-amon  county,  sprayed  with  a  25  per  cent,  emulsion  showed 
no  sign  of  injury  on  the  12th  of  the  following-  July,  and  a  few 
peach-trees  on  these  premises  treated  in  the  same  way  and  at  the 
same  time  were  also  unharmed. 

FIELD  USE  OF  THE  LIME,  SALT,  AND  SULPHUR  WASH. 

From  December  9,  1901,  to  April  15, 1902,  all  peach-trees  receiv- 
ing- insecticide  treatment  by  my  field  parties  were  sprayed  with  few 
exceptions  with  a  mixture  of  lime,  sulphur,  and  salt,  known  as 
the  "  California  wash,  "  and  as  a  matter  of  convenience  in  spray- 
ing- mixed  orchards,  some  trees  of  other  kinds  received  the  same 
treatment.  This  wash  was  used  on  433  different  premises  in  13 
infested  districts,  but  owing-  to  occasional  deficiencies  in  detail  in 
operators'  reports  the  total  number  of  trees  to  which  it  was  ap- 
plied cannot  be  precisely  given.  Separate  mention  is  made  of  its 
use,  however,  on  4,976  peach-trees,  463  plum,  586  apple,  111  pear, 
31  quince,  and  various  other  kinds  sufficient  to  bring-  the  distin- 
guishable total  up  to  9,000  trees. 

During-  this  period  of  four  months  of  southern  Illinois  winter, 
the  weather  was,  of  course,  widely  various.  The  season  was,  as  a 
whole,  rather  unusually  favorable  to  insecticide  work,  but  rains, 
sleets,  snows,  and  freezing  weather  came  frequently  enough  to  test 


1902.]  THE   SAN   JOSE   SCALE.  4&> 

quite  fully  the  general  effect  of  the  weather  on  the  efficiency  of  the 
insecticide.  Although  no  exact  account  of  the  results  over  all  the 
great  area  treated  can  now  be  given,  a  general  statement  may  be 
made  that  the  effect  has  been  excellent  and  entirely  satisfactory  so 
far  as  I  now  can  judge. 

To  secure  an  exact  basis  for  a  general  judgment  of  the  out- 
come I  sent  Mr.  Titus  in  August,  1902,  to  examine  orchards 
treated  with  this  wash  the  previous  winter  and  spring,  and  I  have 
his  report  of  the  results  of  an  inspection  of  25  orchards  in  four  dif- 
ferent localities, — Summerfield,  Makanda,  Albion,  and  Browns, — 
and  of  many  town  lots  at  the  first  and  last  of  these  places.  Al- 
though these  localities  inspected  formed  but  a  small  part  of  the 
number  treated,  they  constitute  a  larger  and  more  varied  experi- 
ment with  this  wash  than  has  hitherto  been  attempted  anywhere 
east  of  the  Pacific  region,  and  a  report  of  results  will  no  doubt  be 
appreciated  at  this  time. 

Formulas  for  the  California  wash  have  varied  considerably  in 
the  literature  of  the  subject,  and  as  it  is  possible  that  conflicting 
statements  concerning  its  value  may  be  due  in  part  to  these  varia- 
tions in  composition,  the  following  description  of  the  wash  used 
during  the  winter  in  Illinois  will  have  its  value  in  this  connection. 
The  mixture  was  made  as  follows  :  Fifteen  pounds  of  stone  lime 
were  slaked  in  a  kettle  over  a  fire  ;  fifteen  pounds  of  sulphur  were 
sifted  or  stirred  in  as  the  lime  was  slaking,  these  materials  being 
boiled  vigorously  until  the  lime  and  sulphur  were  entirely  dissolved 
—usually  something  over  an  hour ;  and  fifteen  pounds  of  salt  were 
then  put  in  and  the  whole  was  boiled  a  quarter  of  an  hour  longer. 
Enough  hot  water  was  added  to  make  fifty  gallons,  and  the  mix- 
ture was  sprayed  while  warm  through  a  nozzle  with  a  large  cap 
for  a  coarse  spray.  When  the  material  first  dried  on  the  tree  it 
gave  the  bark  a  saffron-yellow  color,  which  changed  in  twenty- 
four  hours  to  a  dull  green  and  then  gradually  faded  to  a  greenish 
gray. 

The  California  Wash  at  Summerjield. — No.  1.  One  hundred 
and  forty-five  peach-,  plum-,  and  pear-trees  sprayed  on  the  place  of 
Wm.  Hagemann  between  March  29  and  April  2.  Practically  all  of 
these  trees  were  badly  infested  with  the  scale.  On  the  29th  of 
March  the  weather  was  clear  at  first,  with  the  temperature  rang- 
ing from  48  to  66  degrees,  but  a  hard  rain  fell  in  the  afternoon 
with  a  light  northwest  wind.  From  March  31  to  April  2  the 
weather  was  continuously  cloudy  but  there  was  no  rain;  the  wind, 
northwest  and  west,  from  brisk  to  high;  and  the  temperature  ranged 
from  36  to  62  degrees. 


4QO  BULLETIN  NO.  8o.  [October, 

August  16  several  peach-  and  pear-trees  were  examined  on  this 
place  and  one  thousand  scales  were  carefully  examined,  pains  be- 
ing- taken,  as  in  all  other  cases  on  this  trip,  to  select  the  scales 
from  all  parts  of  the  tree.  Not  a  living  scale  was  found  on  this 
place. 

No.  2.  Twenty-three  slightly  infested  peach-trees  sprayed 
March  22  and  24  in  the  orchard  of  Messrs.  B.  and  A.  Baer.  The 
weather  was  clear  on  the  first  of  these  days  but  cloudy  the  second, 
the  temperature  ranging  from  42  to  72  degrees.  August  16  no 
living  scales  could  be  found. 

No.  3.  Twenty-four  badly  infested  peach-trees  belonging  to 
Mrs.  Mary  Reibold  treated  the  15th  and  18th  of  March,  the  first 
day  cloudy  throughout  with  a  temperature  ranging  from  54  to  62 
degrees,  the  wind  at  first  south,  changing  to  northwest  at  four 
o'clock,  rain  from  noon  onward.  March  18,  clear  all  day  and  cool, 
temperature  from  20  to  34  degrees,  with  light  wind.  August  20,  no 
living  scale  to  be  found. 

No.  4.  Eighty  peach-  and  plum-trees  on  the  premises  of 
Daniel  Krehbiel  sprayed  March  6-8  and  14-15.  The  weather  was 
cloudy  on  all  these  days,  and  rain  began  on  the  afternoon  of  the 
last.  Three  thousand  specimens  of  the  scale  examined  August  20 
and  but  two  found  alive,  both  partly  grown.  They  had  evidently 
come  from  an  infested  hedge  in  close  proximity. 

No.  5.  On  several  town  lots  belonging  to  Mr.  John  Eicher  17 
trees  were  sprayed  with  lime,  sulphur,  and  salt  March  10,  and 
August  20  no  living  scales  could  be  found. 

No.  6.  Forty  trees  were  sprayed,  a  part  of  them  with  lime, 
sulphur,  and  salt,  on  the  town  property  of  Thomas  Keith  March 
10.  August  20  no  living  scale  could  be  found. 

The  California  Wash  at  Makanda. — No.  1.     On  the  place  of 

Mr.  S.  A.  Carr,  near  Makanda,  457  peach-trees  were  sprayed  with 

lime,  sulphur,  and  salt  late  in  December,  beginning  with  the  24th. 

The  weather  was  very  bad — cold,  with  much   sleet.     August  16 

living  scale  could  be  found  on  these  trees. 

No.  2.  On  the  place  of  Mr.  S.  Y.  Dickerson,  1,743  trees  treated 
with  lime,  sulphur,  and  salt  at  intervals  throughout  the  season 
from  January  2  to  March  10  appeared  wholly  free  from  living  scale 
August  16.  In  addition  to  a  general  inspection  of  these  trees  2, 000 
scales  were  critically  examined  and  none  found  alive. 

No.  3.  Thirty-three  peach-trees  were  treated  December  31 
with  the  California  wash  in  the  orchard  of  Lammer  Brothers,  near 
Makanda,  the  weather  being  clear  and  the  temperature  about  40 


IQ02.]  THE   SAN   JOSE   SCALE.  49! 

degrees.     August  16  no  scales  were  found  alive  in  this  orchard 
where,  besides  a  general  inspection,  2,000  were  examined  critically. 

No.  4.  On  the  place  of  J.  W.  and  J.  E.  Herrn  140  peach-  and 
plum-trees  sprayed  with  the  California  wash  March  19  and  20, 
weather  partly  cloudy  but  without  rain,  thermometer  40  to  50  de- 
grees. August  16  no  living  scale  could  be  found. 

No.  5.  In  the  orchard  of  J.  S.  Springer  about  190  peach-  and 
plum-trees  sprayed  with  lime,  sulphur,  and  salt  at  various  dates 
in  January,  February,  and  March.  Four  thousand  scales  critically 
examined  by  Mr.  Titus  August  16,  but  none  found  alive. 

No.  6.  One  hundred  and  sixty-two  peach-trees  and  seven 
plums  treated  March  24  to  April  4  on  the  premises  of  W.  H.  Lipe. 
Sky  cloudy  throughout  but  no  rain.  No  living  scales  found  August 
16  by  general  inspection  or  on  a  critical  examination  of  500  speci- 
mens. 

All  the  orchards  treated  by  my  parties  in  this  section  were 
found  in  fine  condition,  although  some  of  the  worst  infested  trees 
had  been  lately  attacked  by  the  bark-borer,  Scolytus  rugulosus—a.n 
occurrence  to  be  attributed  to  the  diminished  vitality  of  the  trees 
due  to  the  San  Jose  scale. 

The  California  Wash  at  Albion. — No.  1.  One  hundred  and 
fifty-seven  peach-trees  treated  with  lime,  sulphur,  and  salt  in  the 
orchard  of  Hodgson  Brothers,  near  Albion,  April  5-15,  the  weather 
clear  throughout.  The  buds  were  unfolding  at  this  time,  and  the 
work  was  suspended  at  the  latest  date  on  account  of  the  appear- 
ance of  the  leaves.  August  21  the  peach-trees  sprayed  were  in- 
spected, but  no  living  scale  could  be  found.  Of  a  thousand  scales 
examined  none  were  alive. 

No.  2.  In  the  orchard  of  Mr.  F.  A.  Kenyon  225  medium-sized 
peach-trees  were  sprayed  March  18  to  April  2.  Two  thousand 
specimens  examined  August  21  and  two  of  them  alive.  No  other 
living  scales  seen  in  this  orchard. 

No.  3.  On  the  town  lots  of  Anna  C.  Ferriman  23  peach-trees 
and  4  plums  were  sprayed  April  7  and  8,  the  weather  being  fair. 
August  21  no  living  scale  was  found. 

No.  4.  On  the  town  lots  of  Samuel  Churchill  (administrator) 
37  peach-trees  and  12  plums  were  sprayed  April  5  and  7,  the 
weather  clear  except  for  rain  beginning  at  3  o'clock  p.  m.  on  the 
5th.  Five  hundred  scales  critically  examined  August  21  and  no 
living  ones  found. 

The  California  Wash  at  Browns. — No.  1.  Three  hundred  and 
five  peach-trees  sprayed  February  10-14  on  the  place  of  Atkinson 
Taylor,  the  weather  being  variable,  with  snow  all  day  on  the  10th 


492  BULLETIN  NO.  80.  [October, 

and  on  the  evening-  of  the  llth.     Four  thousand  scales  examined 
August  21  and  22  on  the  peach-trees  sprayed  and  none  found  alive. 

No.  2.  In  the  orchard  of  George  Briggs  22  peach-trees  treat- 
€d  with  lime,  sulphur,  and  salt  February  1-5,  the  weather  cloudy 
throughout.  One  thousand  scales  examined  August  21  and  none 
found  alive. 

No.  3.  Eighty-nine  peach-,  apple-,  pear-,  and  plum-trees,  but 
-mainly  the  first,  sprayed  with  lime,  sulphur,  and  salt  February  25 
to  March  4.  These  trees  were  very  large  and  badly  infested.  The 
weather  was  clear  throughout  except  on  the  4th,  which  was  cloudy 
without  rain.  Aug.  22  no  living  scales  could  be  found  on  the  peach. 

No.  4.  Thirteen  peach-trees  sprayed  with  lime,  sulphur,  and 
salt  on  the  town  lot  of  Mary  E.  Marriott  February  6,  the  weather 
being-  clear.  Five  hundred  scales  examined  and  three  found  alive. 
These  were  armored  specimens,  the  only  ones  found  alive  at  this 
place,  although  several  town  premises  besides  those  mentioned 
above  were  carefully  inspected. 

3,931  trees  in  all  had  been  sprayed  with  the  California  wash  by 
my  field  parties  on  the  premises  inspected  by  Mr.  Titus  in  August. 
Besides  making-  a  careful  general  examination  of  these  trees  and 
finding-  no  living-  scales  he  critically  scrutinized,  one  by  one,  21,500 
individuals  and  found  but  seven  of  them  alive.  There  were  no 
crawling-  young-,  and  none  of  these  living-  scales  had  reached  the 
age  of  reproduction. 

GENERAL  SUMMARY. 

Four  insecticides  have  been,  extensively  used  as  winter  ap- 
plications for  the  San  Jose  scale  in  our  general  orchard  work  of  the 
past  three  years  in  Illinois;  hydrocyanic  acid  gas,  whale-oil  soap, 
kerosene  emulsion,  and  the  California  wash  of  lime,  sulphur,  and 
salt,  the  first  being  applied  by  fumigation  and  the  others  as  liquid 
sprays. 

All  are  efficient  destroyers  of  the  scale  under  favorable  con- 
ditions, but  the  operation  of  fumigation  is  practically  restricted 
to  comparatively  small  trees  and  to  comparatively  mild  and  quiet 
weather.  The  California  wash  has  an  evident  advantage  in  per- 
sistence of  effect,  which  amounts  to  an  appreciable  protection  of 
the  tree  against  immediate  reinfestation. 

These  four  insecticides  differ  materially  in  safety,  in  cost,  and 
in  convenience  of  application.  Fumigation  with  hydrocyanic  acid 
gas  and  spraying  with  the  California  wash  are  perfectly  safe  to 
all  trees  and  shrubs  if  applied  after  the  old  leaves  have  fallen  and 
before  the  young  leaves  have  put  forth  ;  whale-oil  soap  is  likely 


I9O2.]  THE    SAN   JOSE   SCALE.  493 

to  destroy  the  fruit  buds  of  the  peach  if  used  before  these  have  be- 
gun to  swell  in  spring;  and  the  kerosene  emulsion  in  strength  suf- 
ficient to  insure  the  destruction  of  the  scale  is  uncertain  in  its  ac- 
tion on  the  more  delicate  kinds  of  trees, — the  peach  especially, — 
and  on  those  of  any  kind  which  are  in  poor  condition.  Serious  in- 
jury has  occasionally  been  done  to  the  peach,  and  in  one  case  to 
apple,  by  an  emulsion  containing  only  20  per  cent,  of  kerosene, 
which  is  rather  below  the  minimum  strength  at  which  this  mix- 
ture should  be  used  for  the  destruction  of  the  scale.  A  twenty- 
five  per  cent,  emulsion,  on  the  other  hand,  is  usually  harmless  to 
the  apple  and  pear,  but  has  proved  in  our  work  to  be  highly 
dangerous  to  the  peach. 

The  cost  of  insecticide  treatment  includes  the  expense  of  the 
original  equipment,  that  of  the  materials  consumed,  and  that  of  the 
preparation  and  application  of  the  insecticide.  In  respect  to  cost 
of  equipment  fumigation  is  by  far  the  most  expensive,  especially 
if  the  trees  to  be  treated  are  large,  but  the  three  insecticide  sprays 
are  prepared  and  applied  by  the  aid  of  practically  the  same  appa- 
ratus. 

The  cost  of  preparation  and  application  is  not  materially  dif- 
ferent for  the  four  insecticides  under  discussion,  and  will  at  any 
rate  vary  greatly  in  practice  according  to  individual  circumstances. 
With  respect  to  cost  of  materials,  the  fumigation  process  is 
much  the  most  expensive.  At  Rich  view,  where  the  trees  treated 
were  usually  of  medium  size  or  less,  the  cost  was  nine  cents  a  tree 
for  fumigation  materials,  while  at  Sparta,  where  the  trees  averaged 
much  larger,  this  cost  was  eighteen  cents  a  tree.  At  the  latter  place 
whale-oil  soap,  although  applied  only  to  the  largest  trees  as  a  rule, 
was  used  at  a  cost  of  seven  cents  a  tree  for  the  soap  itself.  At 
Carterville  and  Browns  the  average  cost  of  lime,  salt,  and  sulphur 
for  the  California  wash  was  two  to  three  cents,  according  to  the 
size  of  the  trees,  while  the  general  average  per  tree  for  kerosene 
emulsion  as  applied  to  over  5,000  trees  was  two  cents  each. 

In  convenience  of  application  the  preference  belongs  clearly  to 
the  kerosene  emulsion  and  the  California  wash,  the  use  of  whale- 
oil  soap  being  frequently  embarrassed  in  very  cold  weather  by  the 
solidifying1  of  the  solution  in  the  hose  if  the  flow  is  stopped,  and 
the  operation  of  fumigation  being  a  laborious  and  complicated  one 
for  trees  above  medium  size. 

It  follows  from  the  foregoing  that  of  these  various  insecticide 
methods  and  materials  the  best  for  common  use  against  the  San 
Jose  scale  is  spraying  in  winter  with  the  California  wash. 


494 


BULLETIN   NO.   80. 


[  October, 


IQ02.J 


THE   SAN   JOSE   SCALE. 


495 


496 


BULLETIN   NO.   80. 


[October, 


1903.] 


THE    SAN   JOSE   SCALE. 


497 


498 


BULLETIN   NO.   80. 


[  October, 


1902.] 


THE   SAN  JOSE   SCALE. 


499 


BULLETIN   NO.  80. 

PLATE  VII. 


L  October, 


PEAR-TREE  THIRTY-FIVE  FEET  HIGH  INFESTED  BY  SAN  JOSE  SCALE,  NEAR  SPARTA,  ILL. 


IQ02.] 


THE   SAN   JOSE   SCALE. 


501 


502 


BULLETIN  NO.  80. 


[October, 


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